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Jointly Owned Facilities - Related Party (Details)	Dec. 31, 2020 MW
Black Hills Energy, Wyoming Electric | Cheyenne Prairie, Simple-Cycle Combustion Turbine
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	37
Cheyenne Prairie | Black Hills Energy, Wyoming Electric | Cheyenne Prairie, Combined Cycle
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	42.4
Cheyenne Prairie | Black Hills Energy, South Dakota Electric | Cheyenne Prairie, Combined Cycle
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	58
Cheyenne Prairie | South Dakota Electric and Wyoming Electric | Cheyenne Prairie, Combined Cycle
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	100.4
Corriedale Wind Project | Black Hills Energy, Wyoming Electric
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	20
Corriedale Wind Project | Black Hills Energy, South Dakota Electric
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	32.5
Corriedale Wind Project | South Dakota Electric and Wyoming Electric
Jointly Owned Utility Plant Interests [Line Items]
Utility Plant, Megawatt Capacity	52.5
Electric Utilities | Busch Ranch I Wind Farm
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
Power Generation | Busch Ranch I Wind Farm
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%

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- Definition

Utility Plant, Megawatt Capacity

+ References

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- Definition

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+ References

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=115995737&loc=d3e659983-123033

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